The Pygmy Hippopotamus Choeropsis liberiensis (Morton, 1849): Bringing to Light Research Priorities for the Largely Forgotten, Smaller Hippo Species.
Das Zwergflusspferd Choeropsis liberiensis (Morton, 1849): Überblick der Literatur und wichtige Forschungsthemen für das oft vergessene kleinere Flusspferd.
Zool. Garten N.F. 84 (2015): 234-265. ISSN 0044-5169.
An endangered species, the pygmy hippo (Choeropsis liberiensis Morton, 1849) has been housed in captivity since the early 1900s, but systematic, prospective research and peer-reviewed literature remain limited in comparison to other IUCN-listed, charismatic mega fauna. There are just over 350 animals in the ex situ population worldwide, so it is an uncommon resident in zoological collections compared to the larger, ‘common’ or Nile hippo (Hippopotamus amphibius).
Most published information for the pygmy hippo constitutes descriptive accounts of first-hand experiences in various zoological institutions. Here we review, analyze and provide a synthesis of the pertinent literature, aiming to identify and prioritize focal research topics for optimizing ex situ management. The pygmy hippo is continually reported to breed well and thus long-term survival of the species, at least in captivity, is assumed, although we identify several reasons to exercise caution.
Further, we demonstrate that the common perception amongst zoological institutions that the pygmy hippo is easy to manage and experiences limited health and husbandry issues is erroneous. Specific issues affecting the captive population with potential negative implications for long-term sustainability include polycystic kidney disease (PKD), a female-biased sex ratio, obesity, a high neonatal mortality rate, and failure of many breeding pairs to reproduce. We identify several research priorities to help address these concerns, and how the resulting information can be applied to improve management, health and welfare of pygmy hippos in captivity.
Studying the distribution and abundance of the Endangered pygmy hippopotamus (Choeropsis liberiensis) in and around the Gola Rainforest National Park in southeastern Sierra Leone.
Dr. med. vet. Dissertation
Department of Biological Sciences, School of Environmental Sciences of Njala University
The pygmy hippopotamus Choeropsis liberiensis is an endangered and elusive species whose global distribution is restricted to only four countries in the Upper Guinean Forests of West Africa. Exact numbers of individuals surviving in the wild are unknown as well as many other aspects of their ecology and behavior. Within Sierra Leone, the Gola Rainforest National Park (GRNP) and its surroundings as well as the adjacent Tiwai Island seem to host the biggest remaining population. Previous work in the GRNP area suggested that pygmy hippos are mainly distributed along larger streams in the community areas outside GRNP, though no surveys particularly targeted pygmy hippos inside GRNP. Second, past pygmy hippo surveys in GRNP did not follow any standardized survey designs and thus are not repeatable nor is it possible to calculate any pygmy hippo abundance or density. Finally, so far there was no possibility to distinguish different individuals of pygmy hippos which would help to get an idea about the population size of pygmy hippos in and around GRNP. The present study therefore focused on pygmy hippo surveys along streams inside GRNP, on the development and testing of new survey designs and on camera trapping in order to identify different individuals on the camera trap pictures. Twenty three streams were surveyed during 44 survey days between May and December 2013. In total, 56 signs, mainly footprints and dung, were observed and mapped. Comparison with previous results suggests that pygmy hippos are really more abundant in the community area and therefore are not adequately protected by GRNP without involvement of local communities and conservation activities focusing on the community area. Knowledge about pygmy hippo locations should be included into land use planning exercises when farming activities are planned with communities. Two survey designs focusing on 2-ha plots evenly distributed along streams were developed and tested, but further tests are necessary in order to finally decide on their effectiveness and suitability. Due to the high level of anthropogenic disturbance in the deployment area, no pygmy hippos were recorded on camera traps. Future research activities should continue to survey more streams inside GRNP, to test the developed survey designs and to deploy camera traps in order to allow for distinguishing different pygmy hippo individuals.